需要将一个图像复制到另一个图像ROI

Question

我正在尝试将一个图像层复制到另一个图像ROI.我的代码如下.

Mat4b src= imread("path");
Mat3b dest = imread("path");
Rect roi = Rect(179,539,src.cols,src.rows); //src.cols = 1186 and src.rows= 1134 after scaling.
Mat destinationROI = dest(roi);
src.copyTo(destinationROI);
imwrite("destinationROI.png", destinationROI);

输入src是 输入目的地是

但输出得到的是相同的目标图像.然后我试图保存目标ROI befre复制.我得到的输出是哪个是正确的.复制src也有效.但它对dest图像没有任何影响.

Answer 1

这是为了确认@ypnos 受过教育的猜测是正确的(好的电话,顺便说一句).

看看这段代码,它执行与您相同的操作:

#include <opencv2\opencv.hpp>
#include <iostream>
using namespace cv;
using namespace std;


int main()
{
    Mat4b m4b(50, 50, Vec4b(0, 255, 0, 255));   // blue image, 4 channels
    Mat3b m3b(100, 100, Vec3b(255, 0, 0));      // green image, 3 channels

    cout << "After init:" << endl;
    cout << "m4b channels: " << m4b.channels() << endl;
    cout << "m3b channels: " << m3b.channels() << endl << endl;

    Rect roi(0, 0, 50, 50); // roi

    // Create a new header for the data inside the roi in m3b
    // No data copied, just a new header.
    // So destRoi has same number of channels of m3b
    Mat destRoi = m3b(roi); 


    cout << "After roi:" << endl;
    cout << "m4b channels    : " << m4b.channels() << endl;
    cout << "m3b channels    : " << m3b.channels() << endl;
    cout << "destRoi channels: " << destRoi.channels() << endl << endl;

    // destination type != source type
    // destRoi is newly created with the destination type
    // destRoi doesn't point anymore to the data in m3b and has 4 channels now
    m4b.copyTo(destRoi);

    cout << "After copyTo:" << endl;
    cout << "m4b channels    : " << m4b.channels() << endl;
    cout << "m3b channels    : " << m3b.channels() << endl;
    cout << "destRoi channels: " << destRoi.channels() << endl << endl;

    return 0;
}

输出:

After init:
m4b channels: 4
m3b channels: 3

After roi:
m4b channels    : 4
m3b channels    : 3
destRoi channels: 3

After copyTo:
m4b channels    : 4
m3b channels    : 3
destRoi channels: 4

解

使用具有相同通道数的两个矩阵,可以通过:

1. 将两个图像加载为3通道矩阵CV_8UC3.事实上,您发布的图像都是3个频道

2. 使用cvtColor转换为相同数量的渠道,进行投资回报率和复制操作之前.